More particularly, the invention relates to a gas turbine engine including a stator vane for directing hot combustion gases onto rotor blades, the stator vane including a platform disposed at the side of the vane radially inward/outward with respect to the axis of rotation of the engine, the platform having a trailing edge portion downstream with respect to the flow of the hot combustion gases past the stator vane.
A part of one known such engine is shown in FIGS. 1 to 3. This known engine is disclosed in U.S. Pat. No. 5,252,026. FIG. 1 is a longitudinal section through the part. FIG. 2 is a view taken on the line II-II in FIG. 1. FIG. 3 is a view taken on the line in III-III in FIG. 2. The part comprises a stator vane 1 having radially inner and outer platforms 3 and 5, rotor blading 7, a rotor disk 9 to which the rotor blading 7 is attached, and a support and cooling arrangement 11.
The trailing edge 13 of radially inner platform 3 is cooled by air supplied to the edge via a passageway between adjacent parts 15, 17 of support and cooling arrangement 11. This supply is indicated by the arrows 19 in FIG. 1. Rotation of the rotor of the gas turbine engine causes the supplied air to travel circumferentially in the region 21 immediately radially inside the trailing edge 13. This circumferential travel is indicated by arrows 23 in FIGS. 2 and 3. As the air travels circumferentially it cools trailing edge 13. The air then passes via circumferentially extending gap 25 to join the hot combustion gases of the engine. Turbulators in the form of rectangular strips 27 are included on the radially inwardly facing side of edge 13 to increase heat transfer from the edge.
The described cooling in the known engine has certain disadvantages. The cooling air is supplied past high temperature rotating parts of the engine, is heated by both the temperature of these parts and friction with these parts, and therefore is less effective when it comes to cooling trailing edge 13. The shape of the region 21 combined with the nature of the flow through it tends to encourage areas within the region where the flow is relatively stagnant, reducing cooling. If the pressure differential between the region 21 and the path of the hot combustion gases of the engine is relatively high then the cooling air will leave region 21 via circumferentially extending gap 25 relatively rapidly without having spent much time travelling circumferentially in region 21 to cool trailing edge 13.